Plant and Cell Physiology, 1985, Vol. 26, No. 8 1587-1595
© 1985
Article |
Polar Transport of 45Ca2$ across the Elongation Zone of Gravistimulated Roots
1 Department of Biology, Kang Reung National University Kang Woon Do, Korea, 210
2 Department of Botany, Ohio State University Columbus, Ohio 43210, U.S.A.
The movement of calcium across the elongation zone of gravistimulated primary roots of maize (Zea mays L.) was measured using 45Ca2$. Radioactive calcium was applied to one side of the elongation zone about 4 mm back from the root tip and the distribution of radioactivity across the root in the region of application was determined using scintillation spectrometry. The movement of 45Ca2$ across the elongation zone was non-polar in vertically oriented roots. In gravistimulated roots the movement of label was polarized with about twice as much label moving from top to bottom as from bottom to top. A variety of treatments which interfere with gravitropism was found to eliminate the polar movement of 45Ca2$ across the elongation zone. In maize cultivars which require light for gravitropic competency, dark grown roots exhibited neither gravitropism nor polar movement of 45Ca2$ across the elongation zone. Upon illumination the roots developed both gravitropic competency and gravity-induced polar movement of 45Ca2$ across the elongation zone. Similarly, roots of light-grown seedlings lost both gravitropic competency and 45Ca2$ transport polarity upon transfer to the dark. The results indicate a close correlation between calcium movement and gravitropism in primary roots of maize.
(Received July 20, 1985; Accepted September 25, 1985)
CiteULike 
Connotea 
Del.icio.us What's this?